Diffusion and Osmosis

• What is diffusion?

  Movement of particles from high to low concentration
• What is the net movement in diffusion?

  Amount of particles going in minus going out
• How does temperature affect diffusion?

  Higher temperature speeds up diffusion
• Why do some cells have folded membranes?

  To increase surface area for diffusion
• What is the SA:V ratio of single-celled organisms?

  Large SA:V ratio
• Why is a large SA:V ratio important for single-celled organisms?

  Allows sufficient transport of molecules
• What is the SA:V ratio of multicellular organisms?

  Smaller SA:V ratio
• How have multicellular organisms adapted for exchange?

  They have evolved exchange surfaces
• How are gills adapted for gas exchange?

  They have a large surface area
• What maintains a steep concentration gradient in gills?

  Continuous flow of water over gills
• Why are the walls of gill filaments thin?

  To maintain a short diffusion distance
• What is osmosis?

  Movement of water from dilute to concentrated solution
• How does osmosis differ from diffusion?

  Osmosis only involves water molecules
• What must the concentration of bodily fluids be kept within?

  Strict limits
• What does turgid mean in plant cells?

  Vacuole presses against cell edges
• What happens to a plant cell in a concentrated solution?

  It becomes flaccid
• What is plasmolysis in plant cells?

  Cell loses water and shrinks
• How are alveoli adapted for gas exchange?

  They have a large surface area
• Why do alveoli have moist walls?

  To dissolve gases for easier exchange
• What is the equation for respiration?

  Glucose + oxygen → water + carbon dioxide + energy
• What is active transport?

  Movement of molecules against concentration gradient
• What energy source is used in active transport?

  Energy from ATP produced by mitochondria
• What do root hair cells absorb?

  Nitrates and mineral ions
• How are root hair cells adapted for absorption?

  They have a large surface area
• What are the processes of diffusion, osmosis, and active transport?

  • Diffusion: Movement from high to low concentration
  • Osmosis: Movement of water from dilute to concentrated solution
  • Active Transport: Movement against concentration gradient using energy
• What are the differences between passive and active transport?

  • Passive Transport:
  • No energy required
  • Moves with concentration gradient
  • Active Transport:
  • Requires energy
  • Moves against concentration gradient
• What are the adaptations of exchange surfaces in organisms?

  • Large surface area
  • Thin walls for short diffusion distance
  • Moist surfaces for gas dissolution
• What are the control variables in an osmosis experiment with potatoes?

  • Length of potato
  • Volume of solution
• What is the significance of maintaining a steep concentration gradient in gas exchange?

  • Increases the rate of gas exchange
  • Ensures efficient oxygen uptake and carbon dioxide removal
• What is the role of mitochondria in active transport?

  • Produces ATP for energy
  • Powers the movement of molecules against the gradient
• How does temperature influence the rate of diffusion?

  • Higher temperatures increase particle energy
  • Leads to more frequent collisions and faster diffusion
• What is the relationship between surface area and diffusion rate?

  • Larger surface area increases diffusion rate
  • More space for particles to move across
• What is the importance of turgidity in plant cells?

  • Maintains cell structure
  • Supports the plant and prevents wilting
• What happens to plant cells in a concentrated solution?

  • Cells become flaccid and lose structure
  • Can lead to plasmolysis if severe